list incarnations API should also return information about the incarnation state (used template, version, ...)

[defreng]

currently, details about the state of an incarnation is only available when querying details about a specific one.

However, for the UI it would be great if we could also return the information about the used template etc. when listing all incarnations.

Idea

At the moment, reading the "used template version "is very expensive/slow, because it needs to be read from the target git repository. We would need to introduce some "caching" mechanism to be able to quickly retrieve that information for all incarnations.

Alternative: Turn this around and make the .fengine file inside the repo the "cache", while the DB values are the real truth... But what would it mean for fengine?